Transcutaneous O2 and CO2 monitoring of bronchial responsiveness in FEV1 non-responder asthmatics during ketotifen and placebo treatment.

Effects of ultrasonically nebulized distilled water (UNDW) on PtcO2 and PtcCO2 time courses were studied in 26 mild asthmatics (FEV1 non-responders) in basal conditions and monitored after 2, 6, 12 and 18 weeks of randomly allocated treatment with ketotifen 1 mg b.i.d. or placebo. Magnitude and duration of both PtcO2 and PtcCO2 changes due to UNDW inhalation were progressively normalized only by ketotifen. Partial but significant protection against UNDW-induced hyperventilation was achieved after 2 weeks of treatment, complete protection (also against UNDW-induced hypoxia) being achieved later. In view of the CO2 dependency of respiratory drive and the primary structural targets of the hypo-osmotic bronchial challenge employed, these results suggest that ketotifen may affect the mucosal structures of the bronchial airways, thereby acting as a mucosal protective drug.